Sebastopol, CA--Early on, Dan Tow, author of the just-released SQL
Tuning (O'Reilly, US $39.95) realized that the biggest factor in the
performance of a business application is the speed of the SQL it runs. It
took him a little longer to realize just how much room for improvement
typically lies in that SQL--in fact, that the SQL that most affects the
load on a system and the productivity of its end users can usually be
improved by a large factor, often by a factor of two or more. The problem
was finding reliable guidance on just how to tune SQL.

There are two basic issues that most people focus on when tuning SQL: how
to find and interpret the execution plan of an SQL statement and how to
change SQL to get a specific alternate execution plan. Tow provides the
answers to these questions in "SQL Tuning" and addresses a third, even
more critical question: How do you decide which execution plan a query
should use?

The process involved is usually one of frustrating trial and error. As Tow
explains, "Since real business-application queries can easily offer
billions of alternative execution plans, tuning without a systematic
method to choose your target execution plan is hopelessly inefficient. The
problem is akin to finding yourself lost in strange city without a http://www.oreilly.com/catalog/sqltuning/map:
working eyes and legs are not enough to take you where you need to go."

"SQL Tuning" details a diagram-based method for tuning SQL statements. The
method is not iterative and random, but deterministic: you follow a
well-defined process once, and at the end of that process you will know
the optimal execution plan for the statement in question. The method
involved not only leads you to an optimal plan quickly and in one pass,
but also assures you that it is, indeed, the optimal plan. This last point
is important because you'll know when to stop spending time trying to
improve the execution of a SQL statement and seek improvement through
other means, such as changes to indexes, the database design, or the
application using the SQL.

"Dan doesn't guess," writes Jonathan Gennick in his foreword to the book.
"He doesn't execute an iterative guess-loop, trying one idea after another
in the hope of stumbling across an improvement. Instead, Dan uses an
innovative and mathematically based diagramming method to derive the
optimal, or near-optimal, execution plan for a SQL statement. Then he puts
that plan into effect. And that's it. There's no guesswork, and there's no
uncertainly as to whether further improvement is possible."

Written for readers who already know SQL and have an opportunity to tune
SQL or the database where the SQL executes, "SQL Tuning" includes specific
techniques for tuning on Oracle, Microsoft SQL Server, and IBM DB2. But
since the book focuses on finding the optimum path to the data--which,
according to Tow, is virtually independent of the database vendor--most of
the book covers a vendor-independent solution to the problem.

The perfect companion to O'Reilly's "SQL in a Nutshell," this book will
arm anyone who troubleshoots poorly tuned applications with a reliable and
deterministic method for tuning their SQL queries.

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